sunrpc: Use sendmsg(MSG_SPLICE_PAGES) rather then sendpage

When transmitting data, call down into TCP using sendmsg with
MSG_SPLICE_PAGES to indicate that content should be spliced rather than
performing sendpage calls to transmit header, data pages and trailer.

Signed-off-by: David Howells <dhowells@redhat.com>
Acked-by: Chuck Lever <chuck.lever@oracle.com>
cc: Trond Myklebust <trond.myklebust@hammerspace.com>
cc: Anna Schumaker <anna@kernel.org>
cc: Jeff Layton <jlayton@kernel.org>
cc: Jens Axboe <axboe@kernel.dk>
cc: Matthew Wilcox <willy@infradead.org>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>

diff --git a/include/linux/sunrpc/svc.h b/include/linux/sunrpc/svc.h
index 762d723..f66ec8f 100644 (file)
--- a/include/linux/sunrpc/svc.h
+++ b/include/linux/sunrpc/svc.h
@@ -161,16 +161,15 @@ static inline bool svc_put_not_last(struct svc_serv *serv)
 extern u32 svc_max_payload(const struct svc_rqst *rqstp);
 
 /*
- * RPC Requsts and replies are stored in one or more pages.
+ * RPC Requests and replies are stored in one or more pages.
  * We maintain an array of pages for each server thread.
  * Requests are copied into these pages as they arrive.  Remaining
  * pages are available to write the reply into.
  *
- * Pages are sent using ->sendpage so each server thread needs to
- * allocate more to replace those used in sending.  To help keep track
- * of these pages we have a receive list where all pages initialy live,
- * and a send list where pages are moved to when there are to be part
- * of a reply.
+ * Pages are sent using ->sendmsg with MSG_SPLICE_PAGES so each server thread
+ * needs to allocate more to replace those used in sending.  To help keep track
+ * of these pages we have a receive list where all pages initialy live, and a
+ * send list where pages are moved to when there are to be part of a reply.
  *
  * We use xdr_buf for holding responses as it fits well with NFS
  * read responses (that have a header, and some data pages, and possibly

diff --git a/net/sunrpc/svcsock.c b/net/sunrpc/svcsock.c
index f77cebe..9d9f522 100644 (file)
--- a/net/sunrpc/svcsock.c
+++ b/net/sunrpc/svcsock.c
@@ -1203,13 +1203,14 @@ err_noclose:
 static int svc_tcp_send_kvec(struct socket *sock, const struct kvec *vec,
                              int flags)
 {
-       return kernel_sendpage(sock, virt_to_page(vec->iov_base),
-                              offset_in_page(vec->iov_base),
-                              vec->iov_len, flags);
+       struct msghdr msg = { .msg_flags = MSG_SPLICE_PAGES | flags, };
+
+       iov_iter_kvec(&msg.msg_iter, ITER_SOURCE, vec, 1, vec->iov_len);
+       return sock_sendmsg(sock, &msg);
 }
 
 /*
- * kernel_sendpage() is used exclusively to reduce the number of
+ * MSG_SPLICE_PAGES is used exclusively to reduce the number of
  * copy operations in this path. Therefore the caller must ensure
  * that the pages backing @xdr are unchanging.
  *
@@ -1249,28 +1250,13 @@ static int svc_tcp_sendmsg(struct socket *sock, struct xdr_buf *xdr,
        if (ret != head->iov_len)
                goto out;
 
-       if (xdr->page_len) {
-               unsigned int offset, len, remaining;
-               struct bio_vec *bvec;
-
-               bvec = xdr->bvec + (xdr->page_base >> PAGE_SHIFT);
-               offset = offset_in_page(xdr->page_base);
-               remaining = xdr->page_len;
-               while (remaining > 0) {
-                       len = min(remaining, bvec->bv_len - offset);
-                       ret = kernel_sendpage(sock, bvec->bv_page,
-                                             bvec->bv_offset + offset,
-                                             len, 0);
-                       if (ret < 0)
-                               return ret;
-                       *sentp += ret;
-                       if (ret != len)
-                               goto out;
-                       remaining -= len;
-                       offset = 0;
-                       bvec++;
-               }
-       }
+       msg.msg_flags = MSG_SPLICE_PAGES;
+       iov_iter_bvec(&msg.msg_iter, ITER_SOURCE, xdr->bvec,
+                     xdr_buf_pagecount(xdr), xdr->page_len);
+       ret = sock_sendmsg(sock, &msg);
+       if (ret < 0)
+               return ret;
+       *sentp += ret;
 
        if (tail->iov_len) {
                ret = svc_tcp_send_kvec(sock, tail, 0);